Certain to create a gaping divide between generational and aesthetic camps, Sucker Punch is a largely grim and unpleasant display of technical wizardry wrapped around a story that purports to be inspirational. Enshrouded in a fantastical and dark, heavy metal mindset and populated by characters that resemble standbys in a road company of Showgirls, Zack Snyder's latest CGI action spectacular is constructed to allow for any kind of flight of fancy he can dream up.

But because they're figments of a girl's imagination, nothing is at stake, resulting in minimal suspense or rooting interest. Hot anticipation from fanboys and the strong female angle suggest big box office potential for this Warner Bros. release, at least at the outset, but these constituencies have proved increasingly fickle and unreliable of late.

With the artistic novelty and commercial success of Dawn of the Dead and 300, Snyder quickly vaulted into primetime. But his storytelling skills came increasingly into question with Watchmen and the awful Legend of the Guardians: The Owls of Ga'Hoole, issues that remain in the episodic Sucker Punch, which is built so as to dispense with the need for narrative logic.

The director, who wrote the screenplay with Steve Shibuya, tries to compensate with his visual skills, which are considerable and on display at their best in the disturbing prologue, which in a few minutes reveals how a girl known only as Babydoll came to end up in a Vermont insane asylum in the early 1960s. Relating the sad tale in strongly expressive visual terms that show real aptitude for silent-film storytelling, Snyder quickly shows how Babydoll (Emily Browning) was betrayed by a dreadful stepfather when her mother died and framed for his murder of her younger sister, putting her on the fast track for a lobotomy at the Lennox House for the Criminally Insane, a creepy old joint in the darkest, dankest Victorian tradition.

However, the social hall has been transformed into a seedy nightclub, where the girls receive dance instruction from an Eastern European "doctor" (Carla Gugino) and then perform for select big shots glad-handed by the establishment's sleazy proprietor, Blue (Oscar Isaac). The teeny Babydoll quickly becomes tight with sisters Sweet Pea (Abbie Cornish) and Rocket (Jena Malone) and tough chicks Blondie (Vanessa Hudgens) and Amber (Jamie Chung) and is given the potential means of escaping Lennox by a gringo Wise Man (Scott Glenn) who presides over an Asian temple. He presents her with a list of five items she must retrieve on a series of hair-raising adventures.

The set-up prescribes that Babydoll enters the world of her imagination whenever she dazzles her special clientele with her dancing (which we never see) and fights the good fight with her girl team, which will somehow facilitate their mutual escape from the asylum. Audiences who have no problem with this fabricated cause-and-effect mechanism will probably be fine with the film, which in relatively quick succession presents the girls engaged in wild warfare in an assortment of scenically perilous settings, including World War I battlefronts, an ancient castle guarded by winged fire-breathing beasts and a world filled with Robocop-style warriors.

These blazing, slashing, swooping, diving, roaring, screaming, demolishing battles, which employ a variety of cool aircraft and the most exotic weapons imaginable, are the meat of Sucker Punch and are choreographed in an epic manner only possible with advanced CGI. The explosions, spearings, decapitations and all-out mayhem, much of it executed with the sort of elegant moves and delayed aerial suspension pioneered in The Matrix, will delight fans who crave this sort of thing from movies above all else.

But the dreamlike or imaginary context in which these sequences are presented automatically drains them of any sense of engagement; just as you can't die in your own dreams, so, too, nothing bad can really happen to the five girls in these adventures, where the rules of engagement are anything Snyder wants them to be.

This still leaves real life inside the asylum, of course, where things do get hairy and take a couple of startling turns before the longed-for escape can be attempted. But, even then, the climactic inspirational spin about the abiding powers of the imagination feels either like a theme unrealized by the film itself or a slogan tacked onto an insufficiently coherent concept.

Led by Isaac's thinly mustachioed slime-bucket asylum entrepreneur, the baddies are distinctly unappetizing company, while the girls, often in heavy performance makeup and looking off-puttingly (rather than fetchingly) vulgar, don't entirely gel. For starters, physically, they don't remotely belong in the early 1960s; even though cultural realism couldn't be further from the film's concerns, why specifically set it then if you're going to ignore period plausibility? Browning's dyed platinum hair is distracting for such a young character at the time, most of the dialogue is blatantly contemporary, and the wall-of-sound music, much of it consisting of elaborate re-dos of the likes of Jefferson Airplane, the Beatles, Queen and Iggy Pop, sometimes effective in their own right, provides an additional level of historical dislocation.